1. Field of the Invention
This invention relates to a process for the polymerization of 1-monoalkyl (C.sub.1 -C.sub.4)dimethylsilyl-1-propynes.
2. Description of the Prior Art
A variety of processes for the preparation of polymers of acetylene compounds have been known and investigated. These processes commonly have several problems such as a difficulty in obtaining high molecular weight polymers and a low yield.
On the other hand, few studies on the polymerization of 1-monoalkyldimethylsilyl-1-propynes which are one of di-substituted acetylene compounds have been made since they have poor reactivity. In recent years, however, Higashimura et al developed catalysts effective for obtaining high molecular weight polymers of the propynes, which is known from U.S. Pat. No. 4,755,193 and Japanese Laid-open Patent Application No. 59-155409. In these publications, it is stated that polymers of 1-monoalkyl(C.sub.1 -C.sub.4)dimethylsilyl-1-propynes are obtained by polymerization of 1-monoalkyl(C.sub.1 -C.sub.4)dimethylsilyl-1-propynes in the presence of a transition metal compound of Group V of the Periodic Table. In this process, a relatively high polymerization temperature is used ranging from 30.degree. to 100.degree. C., within which a higher temperature is favored and a long reaction time of from 12 to 36 hours is necessary. The 1-trimethylsilyl-1-propyne polymer obtained by the above process has very high gas permeability but its characteristic properties degraded considerable. This is reported by Higashimura et al (Journal of Applied Polymer Science: JAPS, Vol. 30, pp., 1605-1616, 1985). According to this literature, when the polymer is thermally treated at 100.degree. C. for about 5 hours, the oxygen permeability coefficient (Po.sub.2) reduced to 1/5 of the initial value.